Why did she get to make the decision anyway, I would have said screw you, if you don't want to sleep in the same bed YOU sleep on the floor... inconsiderate. Stepping on your face should be your justification to bitch slapping her.

Wow, what's so wrong with sharing a bed with a sibling? unless the OP is a perv that's gonna try something on her, I don't see why not, it's just dumb, I've shared a bed with my brother on a number of occasions when we didn't have any rooms free, sure I didn't like it as I'd rather sleep alone, but you get over it as it doesn't matter much once you're asleep.